/* =========================================================================
   layout.css — page shell, header/footer chrome, TOC sidebar, article grid
   ========================================================================= */

/* ---- Site header / footer -------------------------------------------- */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
}
.site-header-inner {
  max-width: var(--page-max-width);
  margin: 0 auto;
  padding: var(--space-3) var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  flex-wrap: wrap;
}
.site-title {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: 0.01em;
  color: var(--color-ink);
  text-decoration: none;
}
.site-nav {
  display: flex;
  gap: var(--space-4);
  font-size: 0.9rem;
}
.site-nav a {
  color: var(--color-ink-muted);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
}
.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--color-ink);
  border-bottom-color: var(--color-accent);
}
.theme-toggle {
  border: 1px solid var(--color-border-strong);
  background: var(--color-bg-raised);
  color: var(--color-ink);
  border-radius: var(--radius-md);
  padding: var(--space-1) var(--space-2);
  cursor: pointer;
  font-size: 0.85rem;
}

.site-footer {
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-6);
  padding: var(--space-4) var(--gutter);
  color: var(--color-ink-muted);
  font-size: 0.85rem;
  text-align: center;
}
.site-footer a { color: var(--color-ink-muted); }

/* ---- Page shell / TOC sidebar ----------------------------------------
   Flexbox handles TOC placement as a real sticky sidebar (not a hack).
   Sidenote placement, below, uses a different technique (float into
   reserved padding) because it needs per-paragraph vertical alignment
   that flex/grid can't give without JS. */
.page-shell {
  max-width: var(--page-max-width);
  margin: 0 auto;
  padding: var(--space-5) var(--gutter) var(--space-6);
  display: flex;
  gap: var(--space-5);
  align-items: flex-start;
}

.toc {
  flex: 0 0 var(--toc-width);
  position: sticky;
  top: var(--space-4);
  max-height: calc(100vh - 2 * var(--space-4));
  overflow-y: auto;
  border: none;
}
.toc summary {
  display: none; /* shown only on narrow viewports, see media query below */
}
.toc-list, .toc-list ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
.toc-list ul { padding-left: var(--space-3); }
.toc-list a {
  display: block;
  padding: var(--space-1) 0;
  color: var(--color-ink-faint);
  text-decoration: none;
  font-size: 0.85rem;
  line-height: 1.4;
  border-left: 2px solid transparent;
  padding-left: var(--space-2);
}
.toc-list a:hover { color: var(--color-ink); }
.toc-list a.active {
  color: var(--color-accent);
  border-left-color: var(--color-accent);
  font-weight: 600;
}
.toc-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-ink-faint);
  margin: 0 0 var(--space-2);
}

.article-body-wrap { flex: 1 1 auto; min-width: 0; }

/* ---- Article header (title / byline / abstract) ----------------------- */
.article-header { max-width: var(--content-max-width); margin: 0 auto var(--space-5); }
.article-header h1 { margin-top: 0; font-size: 2.6rem; }
.byline {
  font-family: var(--font-sans);
  font-size: 0.92rem;
  color: var(--color-ink-muted);
  margin-bottom: var(--space-4);
}
.byline .author { color: var(--color-ink); font-weight: 600; }
.byline .affiliation { color: var(--color-ink-faint); }
.abstract {
  background: var(--color-bg-raised);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  font-size: 0.98rem;
}
.abstract-label {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-accent);
  margin-bottom: var(--space-2);
}

/* ---- Article body + margin notes --------------------------------------
   article-body's own box reserves padding-right for the sidenote column;
   sidenotes float into that padding (Tufte-CSS technique) so each note
   lines up with the paragraph that references it, with no JS needed. */
.article-body {
  max-width: calc(var(--content-max-width) + var(--sidenote-width) + var(--space-4));
  padding-right: calc(var(--sidenote-width) + var(--space-4));
  margin: 0 auto;
}
.article-body > * { max-width: var(--content-max-width); }

.sidenote-number {
  cursor: help;
  color: var(--color-accent);
}
.sidenote-number::after {
  content: counter(sidenote);
  counter-increment: sidenote;
  vertical-align: super;
  font-size: 0.7em;
  font-family: var(--font-sans);
  margin-left: 1px;
}
.article-body { counter-reset: sidenote; }

.sidenote {
  float: right;
  clear: right;
  width: var(--sidenote-width);
  max-width: var(--sidenote-width);
  margin-right: calc(-1 * (var(--sidenote-width) + var(--space-4)));
  margin-top: 0.1em;
  font-family: var(--font-sans);
  font-size: 0.82rem;
  line-height: 1.5;
  color: var(--color-ink-muted);
}
.sidenote::before {
  content: counter(sidenote) ". ";
  font-weight: 600;
  color: var(--color-accent);
}

/* ---- Figures / widget containers --------------------------------------- */
figure.widget, figure.figure {
  max-width: none;
  width: 100%;
  margin: var(--space-5) 0;
  background: var(--color-bg-raised);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  box-shadow: var(--shadow-card);
}
figure.figure.full-bleed,
figure.widget.full-bleed {
  width: calc(100% + var(--sidenote-width) + var(--space-4));
}
figcaption {
  margin-top: var(--space-3);
  font-size: 0.85rem;
  color: var(--color-ink-muted);
}
figcaption .fig-number { color: var(--color-ink); font-weight: 600; }

/* ---- References / appendix --------------------------------------------- */
.references ol { padding-left: 1.4rem; font-size: 0.92rem; }
.references li { margin-bottom: var(--space-2); }
.references a { word-break: break-word; }

/* ---- Responsive: collapse TOC + sidenotes below ~1150px ---------------- */
@media (max-width: 1150px) {
  .page-shell { display: block; padding-top: var(--space-4); }
  .toc {
    position: static;
    max-height: none;
    width: 100%;
    margin-bottom: var(--space-4);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-2) var(--space-3);
  }
  .toc summary {
    display: block;
    cursor: pointer;
    font-family: var(--font-sans);
    font-weight: 600;
    font-size: 0.85rem;
    padding: var(--space-1) 0;
  }
  .toc[open] summary { margin-bottom: var(--space-2); }

  .article-body {
    max-width: var(--content-max-width);
    padding-right: 0;
    margin: 0 auto;
  }
  .sidenote {
    float: none;
    clear: both;
    width: auto;
    max-width: none;
    display: block;
    margin: var(--space-2) 0 var(--space-3);
    padding: var(--space-2) var(--space-3);
    background: var(--color-bg-raised);
    border-left: 3px solid var(--color-accent);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  }
  figure.widget.full-bleed,
  figure.figure.full-bleed { width: 100%; }
}

@media (max-width: 640px) {
  html { font-size: 17px; }
  .article-header h1 { font-size: 1.9rem; }
  .page-shell { padding-left: var(--space-3); padding-right: var(--space-3); }
}